Clonidine derivs. contg. tyrosine fragment - useful for radioimmunoassay of antihypertensive clonidine

摘要

Clonidine derivs of formula (I) and their acid-addn salts are new. In (I) Ar is p-hydroxyphenyl (Ia) or diiodo-p-hydroxyphenyl (Ib) (Ia) is prepd by reacting 3,5-dichloro-4- (2-imidazoliden)amino -benzoic acid (II) with tyrosine methyl ester (III) in the presence of a carbodiimide, esp N-ethyl-N'-(3-dimethylaminopropyl)-carbodiimide (EDC). (Ib) is prepd by reacting (Ia) with iodine (espiodine-125), pref. formed in situ from an alkali metal iodide and an oxidising agent, esp Na N-chloro-p-toluenesulphonamide (IV). (Ib) contg radioactive iodine is useful as a tracer for radioimmunoassay of cloridine, giving higher sensitivity than prior art tracers. (Ia) is an intermediate for (Ib).